Process of making aminosalicylic acid



June 16, 1925.

J. F. NORRIS ET AL PROCESS OF MAKING m-mosmcm'c ACID Filed ocuzo, 1922 l/ll/l .L I: 2: m II/lI/l/l/V/l/I/l/f/ Patented .June 16, 1 925.

UNITED STATES PATENT OFFICE.

JAMES B. NORRIS AND EDMUND O. CUMMINGS, O'F CAMBRIDGE, MASSACHUSETTS.

PROCESS OF MAKING AMINOSALICYLIC ACID.

Application filed October 20, 1922. Serial No. 595,753.

To allwhom it may concern:

Be it known that we, J AMES F. NORRIS and I EDMUND O. CUMMINGS, citizens of the able for carrying out this reduction is illus- OOH to form aminosalicylic acid hydrochloride. A still further object of this invention is to provide a cyclic process whereby the TiCl which during t e reduction becomes oxidized, is again converted into TiCl,. The TiCl used for reduction isdispersed in an inorganic acid, such as- H0] or H SO,,

wherein it is wholly or in part in solution or suspension.

In carrying out the reduction a solution of TiCl, in substantially concentrated HCl is electrolytically reduced, forming TiCl During this electrolysis there is a tendency for titanic acid to be recipitated if the concentration of the HC is too low, and since it is desired to avoid this precipitation the HCl should be of high concentration.

An apparatus which has been .found suittrated, more or less diagrammatically, in the accompanying drawing. The apparatus comprises a vessel (1) 'of material capable of resisting the action of the electrolytes, such as lass, the anode (2) and the cathode (3). e electrodes are made of material which will not be attacked. during the electrolysis. For the cathode, carbon or graphite has been found satisfactory, while carbon,

' porce graphite, and metals such as lead, which are not attacked, have been found suitable for the anode. The a paratus shows the use of the porous cup (4 preferably of unglazed lain, which acts as a diaphragm, and surrounds the cathode (3) and is positioned upon the plate (5) at thebottom oi the vessel (1). Other well known types of diaphragms may be used in lieu of the unglazed porcelain cup. The leads (6) and (7) are connected to the electrodes, and the apparatus is provided with the voltmeter (8), ammeter (9) and'adjustable resistance (10) whereby the current passing through the cell may be determined and regulated. The apparatus may also be provided with a stirrer (11) operated by the shaft {12), pulley (13) and belt 14).

A specific example of carrying out the reduction of the TiCl, solution is as follows: A concentrated solution of about 150 c. c. TiCl, is added to about 600 c. c. of concentrated HCl and placed in the compartment containing a cathode of carbon. in

the compartment containing an anode of lead the dilute solution of H SU (ab-"it 5%) is used. The reduction may be carried out at room temperature, or even below room temperature, but by aising the temperature the cathodic current density may be increased without causing evolution of hydrogen, thereby rw'ui ug the time rv' tired lot the reduction of a given amount of TiCl,.

For example, when operating at C. the current density may be increased over 200%.

above that used when operating at about 22 (3., without causing evolution of hydrogen. In carrying out the reduction at ordinary room temperature a cathodic current density of about 7 amperes per sq. decimeter may be employed and if theopcration is carried on at 5570 C., the current density may be from 9-23 amperes per sq. decimeter, with a voltage across the cell of about 4 volts. The heating efiect of the current causes a rise in temperature to 6070 C.

The reduced solution is analyzed in order to determine the equivalent amount for a iven quantity of benzene-azo-salicylic acid in reducing the latter to aminosalicylic acid hydrochloride.

When the reduction is finished, the solution containing the TiCl is removed from the cathode chamber to a closed vessel and then mixed with the finely ground benzeneazo-salicylic acid, using a slight excess TiCl, solution beyond that necessary forcomplete reduction of the benzene-azo-salicylic acid in order to make certain that all of the benzene-azo-salicylic acid will be reduced. The mixture is, preferably, allowed to stand over night in'the closed vessel and kept stirred. If it is desired to carry on the reduction in reducing the latter b a non-oxidizing) atmosphere, a current of CO may also passed throughthe solution'. It is then heated to boihng in order to complete the reduction.

After boiling the solution is cooled and' filtered in order to remove the bulk of until a specific gravity of about 1.19 is reached. The resulting filtrate may now be electrolytically reduced to regenerate TiCl Over 95% of the original TiCl is usually re? covered.

The above .precipitate containing the aminosalicylic acid hydrochloride and aniline hydrochloride is then combined with the bulk of aminosalicylic acid hydrochloride first obtained and then washed with water which dissolves the aniline hydrochloride, leaving the aminosalicylicacid hydrochloride. The wash liquor may be used in the preparation of benzene-azo-salicylic acid, thus recovering all aniline hydrochlori e.

The aminosalicylic acid hydrochloride is then treated with an alkaline solution in slight excess, and the excess is just neutralized with HCl which will produce the aminosalicylic acid.

This process is very efiicient and yields of more than 94% of the theoretical amount of aminosalicylic acid have-been obtained. The purity of the product is above 80% of the theoretical.

The present invention is not limited to the specific details .set' forth in 'the foregoing examples which should be construed as illustrative and not by way of limitation, and in view of the numerous modifications which may be effected therein without departing from the spirit and scope of this invention, it is desired that only such limitations be imposed as are indicated in the appended claims.

We claim as our invention 1. In a process of preparing an amino acid from a corresponding aryl azo acid, reducing the latter by means of a 'I'iCll solution.-

2. In a process of preparing an amino acid from a corresponding aryl azo acid,

means of TiCl dissolved in concentrate acid.

3. In a process of preparing an amino cylic acid,

4. In a process of preparing an amino I acid from a correspondin aryl azo acid, treating the latter with a TiCl solution and then boiling the resulting composition.

5. In a process of. preparing an amino acid from a corresponding aryl a'zo acid, treating the latter with an excess of acidified TiCl solution and then boiling the re-' sulting composition.

6. In a process of preparing aminosalicylic acid, reducing acid by. means of TiCl,.

7. In a process of preparing aminosalicylic acid, reducing benzene-azo-sa-licylic acid by means of TiCl dissolved in concentrated acid.

8. In a process of preparing amino salicylic acid, reducing benzene-azo-salicylic acid by means of an excess of TiCl inconcentrated acid.

9. In a process of preparing aminosalicylic 'acid, treating benzene-azo-salicylic acid with a TiCl solution and then boiling the resulting composition.

10. In a process of preparing aminosalicylic acid, treating benzene-azo-salicylic acid with an acidified TiGl solution and then boiling the resulting composition.

11. In a process of preparing aminosalicylic acid, reducing. benzene-azo-salicylic acid by means of a TiCl solution and then precipitating dissolved aminosalicylic acid hydrochloride with HCl.

12. In a process of preparing aminosalicylic acid, reducing benzene-azossalicvlic acid by means of an excess of acidified TiCl 13. In a process of preparing aminosali- 'cylic acid, treating benzene-azo-salicylic acid with a TiCl solution, then boiling the resulting composition and then precipitating dissolved aminosalicylic acidv hydrochloride with HCl.

14. In a process of preparing aminosalitreating benzene-azo-salicylic acid with an acidified TiCl solution, then boiling the resulting composition and then preoipitatin dissolved aminosalicylic acid hydrochlori e with HCl.

tures.

JAMES F. NORRIS. EDMUND o. CUMMINGS.

benzene-azo-salicylic In testimony whereof we afiix our signadissolved 

